A warning has been issued about a substance 100 times more toxic than heroin being used as a cutting agent by drug dealers in East Lancashire following a man's death.

Robert Nicolson, 55, died due to a drug overdose because of what the heroin he had taken had been mixed with, an inquest heard.

The hearing, at Blackburn Town Hall, heard Mr Nicolson, who was born in Glasgow, died at a friend's house in Rimington Close, Blackburn, on May 14.

The inquest heard Mr Nicolson, who suffered with drug addiction, had fallen asleep after having taken a cocktail of drugs including cocaine, heroin, and Valium.

A toxicology report from tests conducted after his death showed signs of protonitazene – a synthetic opioid - in his system.

A statement by Dr Edmund Rab, from Sheffield Teaching Hospitals, read out by Coroner Richard Taylor, explained how protonitazene is a new opioid that has a greater amount of morphine and can cause sedation, coma and death, and is likely to have enhanced the toxic effects of the heroin.

Detective Inspector Iain Czapowski, of Lancashire Police, told the court: “The protonitazene is a raised issue across the country.

"It is a very powerful opioid and anyone taking it wouldn’t appreciate they are taking it.

“It is a substance coming from China, but people are cutting it with illegal substances, [and users] won’t know what is in it.”

Concerns were raised by Mr Nicolson's family as to why the friends he was with were unable to call the emergency services sooner, but DI Czapowski said many people don’t recognise the symptoms of an overdose.

The coroner also recognised it was unclear whether any form of intervention could have saved Mr Nicolson's life, but said it would of course have rather been seen.

Mr Taylor said: “He was 54 and had a long-standing history of drug use. He had been with his friend and they had picked up some drugs.

“He had injected cocaine and heroin, and his sister arrived in the early hours but couldn’t wake him and he sadly didn’t wake up.”

Police who attended the scene found no evidence of third-party involvement.

Mr Nicolson had recently been unable to access methadone, having missed two appointments, and without it, his body couldn’t have coped with what he took.

The coroner concluded that the cause of death was a drug-related overdose.